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High calcium in people with cancer

Coping with cancer

This page has information about high calcium levels in people with cancer. There is information about


Why people with cancer can have high calcium

High blood calcium levels are called hypercalcaemia. This is pronounced high-per-kal-see-mee-a. This usually happens in advanced cancer and is rare in people with earlier stages of cancer.

The cancer makes calcium leak out into the bloodstream from your bones, so the level in the blood gets too high. The cancer may also affect the amount of calcium that your kidneys are able to get rid of. If you have bone secondaries, damaged areas of bone can release calcium into your bloodstream. 

Dehydration from being sick a lot or having diarrhoea may also increase calcium levels. It is very important that you do something about this. If not treated, high blood calcium can make you more and more drowsy until you are sleeping nearly all the time. If still not treated, you may go into a coma and eventually die. The types of cancers that are most commonly associated with high blood calcium are

Although less common, high blood calcium can happen in other types of cancer.



It is not always easy for a doctor to spot that you have high calcium. You may not have any definite symptoms. It may be that you just feel a bit unwell or very tired. And the severity of your symptoms doesn’t always match up to the calcium level in your blood. People with a slightly high calcium level can have very severe symptoms, and people with a very high calcium level may only have mild symptoms. Many of the symptoms are common in advanced cancer, even in people who do not have high blood calcium levels.

All this can make it difficult for your doctor to spot high calcium. But the first signs may include

  • Extreme tiredness (fatigue) and lethargy
  • Feeling weak
  • Not wanting to eat much (anorexia)
  • Constipation
  • Loss of concentration and interest in doing things
  • Mild confusion

If high calcium is not treated the symptoms may become much worse and can include

  • Feeling and being sick
  • Drowsiness
  • Passing large amounts of urine
  • Feeling very thirsty
  • Dehydration
  • Confusion
  • Agitation
  • Muscle spasms, tremors.
  • Bone pain and weakness
  • Irregular heart beat
  • Difficulty thinking and speaking clearly
  • Coma and finally death, if not treated

Because calcium plays a role in the normal working of the brain and spinal cord, patients with severely high calcium levels may also

  • Have fits (seizures)
  • Be unable to coordinate muscle movement, which can affect walking, talking and eating
  • Have changes in personality
  • Have hallucinations

If you have high calcium, you will need treatment from your specialist. It can be a life threatening condition if it is not treated. You may have to spend a day or two in hospital to get your calcium levels down.

There is detailed information about managing hypercalcaemia in the next section.

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Updated: 25 May 2016